1. Field of the Invention
The present invention generally relates to a portable apparatus, and especially relates to a portable apparatus that includes an antenna apparatus for UWB (ultra-wide band).
2. Description of the Related Art
In recent years and continuing, UWB radio communication technologies have attracted attention for their capabilities of RADAR positioning and large capacity transmission. Especially, since the approval by the U.S. FCC (Federal Communication Commission) in 2002 of UWB for public uses in a frequency band between 3.1 and 10.6 GHz, developments are being actively undertaken for the utilization of UWB.
Since UWB uses a super-wide band, the antenna apparatus for UWB must be capable of super-wideband transmission and reception.
Further, as applications of the antenna apparatus, portable apparatuses used outdoors can be considered.
An antenna for use at the FCC approved 3.1-10.6 GHz band is proposed by Non-Patent Reference 1; the antenna includes a ground plane and a feeder.
FIG. 1A and FIG. 1B show conventional antenna apparatuses 10 and 20, respectively. The antenna apparatus 10 includes a ground plane 11 and a feeder 12 that is shaped like a reversed circular cone. The feeder 12 is provided on the ground plane 11. The side face of the circular cone shape of the feeder 12 has an angle θ to the axis of the circular cone. By adjusting the angle θ, a desired characteristic is acquired.
The antenna apparatus 20 includes a feeder 22 in the shape of a teardrop, configured by a circular cone 22a and a sphere 22b inscribed in the circular cone 22a. The feeder 22 is arranged on the ground plane 11.
[Non-Patent Reference 1]
“An omnidirectional and low-VSWR antenna for the FCC-approved UWB frequency band” by T. Taniguchi and T. Kobayashi (Tokyo Denki University) in 2003 IEEE AP-S International Symp., volume: 3, pp. 460-463, Jun. 22-27, 2003. (Disclosure on March 22 at B201 classroom).
[Patent Reference 1] JPA 2000-196327.
The conventional antenna apparatuses tend to require a great volume because of the feeder of the circular cone or the teardrop on the ground plane; accordingly, miniaturization and a thinner shape are desired.
Applicant hereto has applied for patenting a UWB flat antenna apparatus 30 with JPA 2005-378396, the basic composition of which antenna apparatus 30 is shown by FIG. 2A and FIG. 2B, whereby a certain degree of miniaturization is attained with a thin structure.
The UWB flat antenna apparatus 30 includes a substrate 31, made of a dielectric material, having an upper surface 31a and a bottom surface 31b. On the upper surface 31a, an antenna element pattern 32 shaped like a home plate and a micro strip line 33 that extends from the antenna element pattern 32 are formed. On the bottom surface 31b, a ground plane 34 is formed countering the micro strip line 33.
The UWB flat antenna apparatus 30 is made smaller and thinner than the antenna apparatuses 10 and 20. Nevertheless, space sufficient to accommodate the UWB flat antenna apparatus 30 has to be provided in a portable apparatus so that further miniaturization and thinner configuration are required by portable apparatuses.